Great response to this puzzle – thank you so much! I was surprised to see the activity in countries like Germany and Singapore this time, in addition to the activity I see in India and US – appreciate all the readers very much.

First correct answer was from Girish Tutakne, and the only correct answer among the younger adults was from Shruti Mittal yet again. Well done both!

While it was easy to solve the puzzle using algebra, but the fun  of the puzzle was solving without it. Here is a link to the solution.

http://www.educreations.com/lesson/view/solution-to-puzzle-42/14654507/?s=IGL3Je&ref=link

Hope you enjoyed the puzzle!